Transformer



July 5, 1927.

L. H. T HULLEN TRANSFORMER Filedl July 15, 1924 IlllII/l/llll/llll/lll/lll lill/Iliff!!lill/111111 I R O T N E N y v4Parana! July s, 1927.l Y

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PATENT jor-FICE.

Louis n. minimun, or Urnn uoN'rcLAiR. New. JERSEY, 4A'ssrcrnoia., BYMESNE Asswimmers, ro zr. c. THULLEN, or LEEroNrA, omo.

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Application `tiled Ju'uly 15, 1924. Serial No. 726,067.

My invention relates to transformers and more particularv to transformers for use in radio reception apparatus, although the 1nvention in its broader aspects is applicable to transformers for other purposes. In 'radio transformers one or more of the windings are commonly traversed by direct current from a battery or similar source of l,direct current. Thev alternating` or oscillating voicel or carrier current also traverses these windings. In order that the core does not become highly magnetized by the combination ofthe two currents,` it is desirlablehby lsome means to increase the reluctance of the magnetic circuit. This reluctance should be a predetermined value dependent upon the amount ofY direct lcurrent traversing the windings so that the core is not ma etized beyond a given point which should e quite low in order that the same Wave form of current is induced in thevsecondary asis in the primary. t f

In order that the shape of the current Wave in the secondary be an exact du licate, or nearly the shape, of the wave of t e current in/.the primary, it is very desirable that the core of the transformer be very highly laminated. This, I have accomplished, byk

using very fine particles of ironl (iron dust) 0 mixed ,to ether with someI form `of a binder so that .tie iron particles are more or'lessl separatedmagnetically by this binder. At the same time they are in sufficient close relation to each other to make a complete mag'- netic path.V Theamount of binderused depends upon the total reluctance that is rdesired in`\the .magnetic circuit.-v For instance, shoulda calculation show that an airgap of acertain amount is desirable in the magnetic l'circuit then a suilicient ercent of binder is used in connection Wit the iron dust to make the magnetic circuit equivalent to this air gap. L It is not new to use iron dust with a binder in other relationships but heretofore, lso far as I am aware, this iron dust has beenused with a minimum amount of binder so as to g'et an iron core with the minimum magnetic reluctance. However, I prefer to put in suicient binder to increase the'reluctance to a predetermined value 4for the reasons mentioned. vt thesame time this ,allows c me to use a greater amount ofbin-der there# by making the entire core structure more substantial. -Heretofore the core of such an article with al small amount of binder has been very fragile and quite expensive.

For certain purposes, therefore, I use a percentage of binder substantiallyl greater han has heretofore been used, so far as I am aware, and the volume of the binder isl preferably between about`2% and about 10% of theN volume of the iron dust. Any suitable binder -may be used such as silicate of soda. Further and more specific objects, features and advantages will more fully appear from the detail description given vbelow takenin connection with the accompanyin sheet of drawings which form a part of t is specification. In the drawings Fig. 1 is aplan Aview of al transformer embodyin one form of my invention. Fig. 2 is ahorizontal section jtaken on the line 2 2 of Fig. 3. Fig. 3 is a vertical section taken on the line 3--3 of Fig. l. Fig. 4 is =,a view of the bottom of the transformer. Fig.v5 is a vertical section illustrating a modification andFig. 6 is. a `lvsimilar section illustrating a'further modilfication. l f

In the drawings 1 represents a suitable base of insulating' material such as hard rub- .ber or ba'kelite provided with downwardly is' cutout on its top l'face as indicated in Fi 3 and 4, and provided with four inwar y and downwardly extending lugs separated extending supporting flanges 2v. The `basel by cut awa spaces at 4. Supported on the lugs Sis t e bottom half 5 of a magnetic structure, which structure is in the form of 'a cup shaped member with a cylindrical u wardl extending wall 6, the bottom of t e j cup sfiaped member 5 having four slots 7 cut through'it opposite the spaces 4 respectively. "The cup shaped'member 5 is'provided with a centrally arranged cylindrical core 8 extending -upwardly from'the bottom of the cup. The cup shaped meniber 5 is moulded-and made up of'a mixture of irondust .(small iron particlesyvand anyfsuib able binder such as silicate of soda as; before mentioned. Over the member 5 is an 1nverted cup shaped member 9 provided with adownwardly extending cylindricalfwall. 10

^having a rabbetedv lower edge at 11 interlocking with a corresponding rabbeted edge on the wall 6. The Vmember 9 is likewise molded and made up of a mixture of iron dust and abinder, and in order. to strengthen and reinforcethe members 5 and 9,I embed therein a series of vwires 12, 13, `14 and 15,

the member 9 being also provided with a centrally arranged downwardly extending and the secondary turns or winding 18 with insulating end members- 19 and 20. The entire members 5 and 9 with the core parts 8 and 1G being mold-ed 'of the mixture ofiron dust and binder, they form a magnetic 'structure which provides a closed magnetic circuit with a central core around which the turns are wound and which structure entirely surrounds and encloscs the core and the primary and secondaryv coils. This structure is, however, divided transversely into two or more removable parts for ease 1n assembling. The parts areuheld rigidly locked together by a bolt 21 passing vertically centrally through the magnetic core `and having a laterally turned end 22 at the bottom engaging under a transverse plate 23 the ends of which engage respectively under two of the lugs 3 on the base member whereby upon tightening up on the nut 24 on the bolt the parts are pulled together and rigidly held in operative position. The base 1 is provided with binding posts 25 and 2G and leads 27 are connected to these binding posts on the underneath side of the base and extend up through two of the slots 7 and in the member 5 to the secondary winding 18. The base 1 is also provided with two binding posts 28 and 29 and leads 30 are con- -that the bundle of iron wires 32 aected with these binding posts on the underneath side of the base and extend up through the other two slots 7 in the members 5 to Vthe primary winding 17.

In Fig. 5 the upper inverted cup shaped member is shown as having a different form of core structure. Instead of an integral core structure of a mixture of iron'dust and a binder, it is provided with a core structure formed of a cylindrical bundle of tine vertical iron wires 31. In Fig. 6 the structure is substantially the same except forming the core structure, extend tothe bottom of thelower. cup shaped member 5, whereby the entire core is made of iron wire.

The object of making the iron core partly of tine wire and partly of moulded iron dust is that I may be able to make a more substantial structure and still make a trans former with a small' amount of eddy euryrent losses. The fine iron wire will make a Core better laminated than if made of sheet laminated steel. At the same time, the permeability of this part of the core will be quite high compared to its sectional area. This is desirable insomuch as it is desirable to get the primary and secondary windings as small as possible. The iron section exterior of that part of the iron circlt that goes through the winding can have as llarge.

a section as desirable as this part is exterlor to the winding.' and in no way miuences its size. The wires 12, 13, 14 and 15 may be either of nonferrous material or othe-rwise.

From the above it will be apparent that I have provided a transformer which is substantially iron clad in type. This is'de- Sirable since it shields the windings from stray fields from outside nearby apparatus.

While I have described my improvements in great detail and with respect to a preferied form thereof, many changes and modications may be made and the invention embodied in widely different forms and for various purposes without departing from the spirit and scope of the invention in its broader aspects. Hence I desire to cover all modifications and forms coming within the language or scope of any one or more of the appended claims.

What I claim as new and desire to Secure by Letters Patent, is:

1. A transformer having a. substantially closed magnetic circuit comprising a' central core and a surrounding magnetic structure. and energizing turns about said core and surrounded by said surrounding magnetic structure, a. substantial part of said magnetic circuit being made up of a mixture of iron dust and a binder in which mixture the volume of the binder is from about 2% to f about 10% of the volume of iron dust.

2. A transformer having a substantially closed magnetic circuit comprising a central core and a surrounding magnetic structure, and energizing turns about said core and surrounded by said surrounding magnetic structure, said surrounding magnetic structure being made up of a mixture of iron dust and a binder in which mixture the volume ot the binder is from about 2% to about 10% of the volume of iron dust.v

3. A transformerhaving a substantially closed magnetic circuit comprising a central core and a surrounding magnetic structure.. and energizing .turns about said core and surrounded by said surrounding magnetic 1 structure, said core being formed of a bundle of i-ron wires and a substantial part of said magnetic circuit being made up of a mixture of iron dust and a binder in which mixture the volume of the binder is from about 2% to about 10% of the volume of iron dust.

4. A transformer having a 'substantial part of its magnetic circuit made up of a mixture of iron dust and a binder in which mixture the volumev of the binder is from 4about 2% to about 10% of the volume of iron dust, and said mixture having'reinforcing members embedded therein.

5. A transformer having a substantially closed magnetic circuit comprising a central core and a surrounding magnetic structure,

said lsurrounding magnetic dust/'and a binder .in which mixture the volume of the binder Ais fffrom about 2% tol about ofthel vvolume of iron dust, and

' closed magnetic circuit comprisnga central said` mixture having reinforcing members* embedded therein.

6. A transformer having a substantially v coreand a surrounding magnetic structure,

and energizing turns labout saidcore and surrounded by said ysurrounding magnetic structure, the magnetic circuit structure being made in a plurality of' parts for easy assembling and a substantial part thereof being made up of a mixture of 3iron dust and ay binder.l

7. A transformer having a substantially closed magnetic circuit comprising a central lcore and a surrounding magneticv structure;

vand energizing turns/about said core and surrounded by said surrounding magnetic structure, the said surroundin structure lbeing made in' a plurality of separable parts and energizing turns about said core ,and v surrounded by said surrounding magnetic f r ease in assembling and a substantial part thereof being made up of a mixture of iron dust and a binder..

8. Ay transformer having 'a substantially closed magnetic circuit comprising'a central core and a surrounding magnetic structure, and energizing-turns about said core and surrounded by said surrounding .magnetic structure, the said surrounding structure being made in a` plurality of separable .parts for ease"in"assenibling and a substantial art thereof bein made up of a'm'ixture of iron dust .and a nder, and said mixture:

having mechanical reinforcing means. f

9. Atransfogmer liaving. afsubstantially structure, the said surrounding structurebeing made lin a plurality of se arable parts for. ease in assembling and a su tantialpart thereof being made up of a mixture of iron dust and a binder, and means for locking er having a substantially vclosed magnetic circuit comprising a central lcorev and a surrounding magnetic structure,

10. A transform and energizing. turns about said coreandj surrounded b said surrounding ma etic structure, sai surrounding structure. ing made up of iron dustand aibinder, 'and being divided' transversely into a pluralityofA separable parts interlocking vwith one anot er. 11. transforiiier -having a substantially closed magnetic circuit comprising acentral core and'a 'surrounding magnetic structure, and energizing turns about said core and Asurrounded by said surrounding m-a lia.

surrounded b "said ysurrounding magnetic structure, sai A'surrounding structure being made up of iron dust and a binder, and 'be-, ing divided transversely into aA plurality of separable yparts'interlocking with one an. 70

`through the transformer for holding said parts together, said mixture having 'me- 85` chanical reinforcing .means and the volume of binder in the-mixture being from about 2%.to about 10% of the volume of iron dlust therein. Q Y

13.,A transformer comprising two cup shaped members facing one another and forming part of the .magnetic circuit ofthe (y transformer and agmag'netic core arranged centrally of said members'.

14. A' transformer 1 comprising two'cup 95 shaped 4members facing one yanother and `forming part ofthe magnetic circuit ofthe transformer land a magnetic 4core arranged. centrally/.of said members, said cup shaped membersthe' g vcomposed of a. mixture of 100 iron duStild-a s uitablebinder. 'f

' 15. LA 'transformer havingaD core ofmag- .netic material, a winding surrounding' the same and 'anienclosing structure of magnetic material entirely surrounding` said.

core and Winding ,and forming part'of the magnetic circuit of the transformer.

16. A transformer having acore of m lg? i' netic material; awinding surrounding t e same and an encl ing structure of magnetic .material entirely surrounding said c ore and rl v .winding and forming part of the ma netic circuit of the transformer, a substantia part of the magnetic-'circuit being formed of\a mixture of iron dust and a bindeinf 1?.'A transformer having a substantially Aclosed magnetic circuit compiising a centra-I `core and ja surroundingmagnetic structure .and energizing turnsabout said core an `surrounded by said vsurrounding magnetic' 120 structure, said surrounding magneticstruc-- ture having apertures 1n one endv thereof through whichieads extend to the-windings y of the transformerl respectively.

18. A transformer havinga substantiallyvv1 42tiv iclosed magnetic circuit comprisingv a central core and 'a surrounding magnetic structure, 'and energizingturns about said core" etic structure. a base df insulatingmaterial-to 13,9.

'and leads from said binding posts structure',

Wvhich said structure is '.secured,L primary A transformer having a central core\ of magnetic material and an enclosing structure of magnetic material entirely surrounding said core, a base of insulating material `and means passing through the core for securing the base to the core and magnetic structure, said core and magnetic structure forming the magnetic circuit ofthe transformer, and a substantial part of said magnetic circuit being made up of a mixture of iion dust and.. a binder in which mixture the volume of the binder isifrom about 2% to about 10% of the volume of iron dust.

21. A transformer having a central `core of magnetic material and an enclosing structure of magnetic material' entirely surround- .ing said core, a base of insulating material and means passing through the core for securing the base to the core and magnetic vsaid core and magneticJ structure forming the magnetic circuit of the transformer, primary and secondary binding posts on said base, and leads therefrom extendingthrough the bottom of the basca-nd said enclosing structure to the primary and 'secondary ofthe transformer. y

22. A transformer having a substantially closedmagnetic circuit comprising a central core and a surrounding magnetic structure, and energizing' turns about said core and surrounded by said surrounding magnetic structure, a substantial part of said mafrnetic circuit being made up of a mixture o iron dust and a binder. r, g

23. A transformer having a substantially closed magnetic circuit comprising a central core and a.A surrounding magnetic structure, and energizing turns about said core and surrounded by said surrounding magnetic structure, said core being formed of a bundle of iron Wires and a substantial part of said magnetic circuit being made up of a mixture of iron dust and a binder.

24;. A transformer having a substantially closed magnetic circuit comprising a central corev and a surrounding magnetic structure, and energizing turns about said core and surrounded by said surroundingmagnetic structure, said surrounding magnetic structure being made up of a mixture "of iron dust .and a binder.

25.V A transformer having a` substantially closedV magnetic circuit comprising a central core and a.- surrounding magnetic structure, and energizing turns about said core and surrounded b said surrounding magnetic structure, sai surrounding magnetic structure being made up of a mixture of iron dust .and a binder and said mixture having reinforcing members embedded therein.

` In testimony whereof -I have signed my name to this specification,

Y LOUIS H. 'THULLEN 

